Explanation:
Saturn's rings form one of the larger sundials known.
This sundial, however, determines only the
season of Saturn, not the time of day.
In 2009, during
Saturn's last equinox, Saturn's thin rings threw
almost no shadows onto Saturn, since the ring plane pointed directly toward the Sun.
As Saturn continued in its orbit around the Sun, however, the ring shadows become increasingly wider and cast further south.
These shadows are not easily visible from the Earth because from our vantage point near the Sun, the rings
always block the shadows.
The above image was taken in August by the
robotic Cassini spacecraft currently orbiting Saturn.
The rings themselves appear as a vertical bar on the image right.
The Sun, far to the upper right, shines through the rings and casts captivatingly
complex shadows on south Saturn, on the image left.
Cassini has been
exploring Saturn,
its rings, and its moons since 2004, and is
expected to continue until at least the maximum elongation of Saturn's shadows occurs in 2017.